Historical Trend in the Number of Breweries in the US

I have heard it said many times that Prohibition killed the brewing industry in the United States, but from my friends at Mother Road Brewery I get a link to a nice graph  from the Brewers Association showing the number of breweries in the United States since 1887. [big version]

Breweries in the US since 1887

This is just a hunch, but it looks like the number of breweries was on a downward trend that was not affected in any way by Prohibition.